A Kinetic Study of the Nonisothermal Decomposition of Palladium Acetylacetonate Investigated by Thermogravimetric and X-
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RECENT advances in solid-state electronics and catalysis[2–4] have often been achieved through the use of organometallic complexes as precursors of high-purity metal phases with the desired composition and topology. In this respect, acetylacetonate complexes have a significant role,[5–8] because they are easily synthesized and purified; their volatility may also be finely tuned for chemical vapor deposition (CVD) applications by the controlled introduction of fluorine atoms. Moreover, the supported metal phase is simply obtained by the controlled thermal removal of acetylacetonate ligands. However, the final properties of the metal phase, particularly for catalytic purposes, are generally depen[1]
BOJAN JANKOVIC´, Assistant Professor, and SLAVKO MENTUS, Professor, are with the Faculty of Physical Chemistry, University of Belgrade, Belgrade, Serbia and Montenegro. Contact e-mail: bojanjan@ ffh.bg.ac.rs Manuscript submitted April 24, 2008. Article published online January 28, 2009 METALLURGICAL AND MATERIALS TRANSACTIONS A
dent on the nature of the chemical interactions between the organometallic complex and the oxide support.[5–9] Thermochemical methods play a primary role in the characterization of the kinetics of the decomposition processes of the supported organometallics, to yield the desired metal phase. Many different approaches have been proposed, ranging from conventional differential thermogravimetric (DTG) studies[6,8] to more specialized flow techniques for catalyst characterization.[10–12] A large amount of information about a catalytic system can be obtained by using thermogravimetric (TG) techniques (working with an appropriate temperature program).[13] From the thermal data, it is possible to achieve information regarding the composition and structure of the different phases of a given sample. Mass changes as a function of the temperature registered through the TG analysis technique are caused by the formation and rupture of chemical bonds at high temperatures, either by processes that cause volatile compounds or by reaction products that modify the sample mass. VOLUME 40A, MARCH 2009—609
The decomposition of organometallic compounds that are in the solid state and that are components of various viscous compositions, such as pastes and polymers, can be regarded as separate techniques. Organometallic compounds of the platinum group can decompose to a metal or an oxide under the influence of: heat, electric discharge, and electron beam and laser radiation; these techniques are employed for the vapor phase decomposition.[14] The decomposition of organometallic compounds in solution is frequently performed thermally, photochemically, electrochemically, or via chemical reduction and hydrolysis.[14–16] Any organometallic platinum group compound is potentially suitable for the formation of films from solution via thermal decomposition. The determining factor is the availability of the compound and its possible commercial production. Palladium is one of the less expensive platinum group metals; the chemistry of it
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